There are lots of posts here on weathering wood. You could add a sealer to whatever you do afterwards to protect the wood.
Put a piece of steel wool in a glass jar with vinegar. Let it sit overnight and paint it on the wood.
Hi Susan: One of the simplest ways to age wood quickly is to apply a paste of baking soda and water, let it dry in the sun, and scrub and wipe it away. Aging wood with baking soda leaches the dark tannins away, resulting in a partially bleached, weatherworn look, similar to a barn or driftwood. Good luck
Here are a couple ideas for you!
This project may help: DIY Reclaimed Cedar Fence Board Accent Wall
Hope this Helps! Jeremy - https://pahjodesigns.com
I use a vinegar and steel wool solution to age wood. The steel wool needs to be the old SOS pads that actually rust. Put them in a jar for a few hours then paint it on the wood.
You can apply a water based stain on them. Varnathane makes one.
This should help: https://thehoneycombhome.com/how-to-age-wood-for-a-weathered-look/
gray wood stain
stain them gray!
this tutorial should help: https://do-daddy.com/how-to-distress-painted-wood-furniture/